1. Field of the Invention
The present invention relates to a receiving station management apparatus for transmitting video and audio signals and, more particularly, to a management apparatus based on the grouping of receiving stations in satellite broadcasting and communication.
2. Description of the Prior Art
In a conventional receiving station management apparatus such as that discussed in Telecommunication Technology Council Inquiry Report No. 17, each receiving station is managed in such a manner that a work key for decrypting encrypted program information and information associated with a contract with each receiving station ("contract information") are transmitted, as individual information, to each receiving station, in order to prevent a party from illegitimately receiving a broadcasting/communication service by altering the information. When the contents of the above information are to be rewritten, individual information is transmitted to each receiving station as a subscriber again (refer to Japanese Unexamined Patent Publication No. 4-115736).
Since this conventional receiving station apparatus transmits a work key and contract information as individual information to rewrite the contents of the information, it takes a longer time for all the receiving stations to receive this information as the number of receiving stations increases.
In existing pay satellite broadcasting, a maximum of 111 packets of scramble information can be transmitted per second. Assuming that 100 packets of individual information are transmitted and, if the total number of receiving stations is 1,000,000, it therefore takes about 13 hours for all the receiving stations to receive the individual information.